1. Field of the Invention
The present invention relates to an image processing system for receiving image data of a document, original, or the like on a pixel unit basis, for converting it into a digital signal, and for processing this digital signal and, more particularly, the present invention relates to an image processing system capable of processing one pixel of image data by both of the binary digital signal and the multivalue digital signal.
2. Related Background Art
Hitherto, there has been generally known an image processing system in which image data such as diagram, document, or the like is read on a pixel unit basis by a photoelectric converting device or the like and converted into a binary digital signal and subjected to processes such as editing, display, storage, and the like. On the other hand, in recent years, there has been developed an image processing system in which image data is converted into a multivalue digital signal and processed in order to process image data having a half tone expression such as a photograph or the like and further to perform image processes such as gradation conversion, edge emphasis, cut-out of a target image data, etc.
However, in the image processing system for performing image processes on the signal (hereinafter, referred to as the binary image data) derived by converting image data into a binary digital signal, the image processes cannot be performed on the signal (hereinafter, referred to as the multivalue image data) derived by converting image data into a multivalue digital signal. In addition, even in the image processing system for performing image processes on multivalue image data, the image processes cannot be performed on the binary image data. In other words these image processing systems lack flexibility.
Hitherto, there has been known a method whereby multivalue image data is expressed as a pseudo half tone by binary image data on the basis of a dither method, a density pattern method, or the like. However, there is a drawback such that the picture quality deteriorates because of the deterioration of the gradation and resolution, the occurrence of the moire, and the like.